David Davis is a former Shadow Home Secretary, and is MP for Haltemprice and Howden.

In March 2003 Khalid Sheikh Mohammed, the supposed mastermind of the 9/11 attacks, was captured in Pakistan. Following his capture, he was waterboarded a horrifying 183 times over the next month, treatment described by internal CIA records as, “a series of near drownings”. The barbarism of the secret CIA torture programme was yesterday finally laid bare in a damning report from the Senate Select Committee on Intelligence.

Treatment such as Khalid Sheikh Mohammed’s was by no means an isolated incident. Hundreds of individuals were subjected to a wide array of inhumane ‘coercive’ techniques.

Ibn al-Shaykh al-Libi, who ran the notorious Al Khaldan training camp which trained al-Qaeda fighters for attacks against the United States, was captured in Afghanistan in November 2001. He was then subjected to torture by American and Egyptian forces. The information that was extracted was used by the US in the months leading up to the Iraq war as evidence of collusion between Saddam Hussein’s regime and al-Qaeda.

We now know that the intelligence that was being sought centred on any links between Iraq and al-Qaeda. But as anyone who has been tortured or waterboarded will tell you, after that level of punishment you will tell your tormentors anything to make them stop. If they demand to know whether al-Qaeda is operational in Iraq then you would fully admit to such a link, regardless of whether such a link even exists.

Inevitably, the information provided by al-Libi and other torture victims proved to be almost entirely fabricated. Yet this was the sort of information upon which the CIA based its assessment of the existence of Iraqi weapons of mass destruction.

When Colin Powell made his presentation to the UN setting out the US’s argument for invading Iraq he claimed that he was presenting “facts and conclusions based on solid intelligence.” We now know how solid this intelligence was. And it was this intelligence that led us into a series of actions that has left hundreds of thousands of Iraqis, and thousands of allied troops, dead, the Middle East in chaos and our moral authority in tatters.

To our enduring shame we were complicit in all of this. Rumours abound that the British Government sought to have our part in the Senate report redacted – and despite being asked several times, the Government has refused to confirm or deny this.

We may not have engaged in torture ourselves, but time and time again we have turned a blind eye – in the rendition programme, in allowing people initially under our control to be taken and subjected to torture, and notably in the case of Abdel Hakim Belhaj. There is now little doubt that the Government operated a secret policy of complicity in torture in the years after 9/11.

The damage done is not just to the innocent prisoners in our charge, or to those killed on the basis of that false intelligence. Our moral standing in the world is utterly compromised. Our reputation, so vital for a small nation that continues to punch above its weight, is irreparably damaged. And when our enemies fabricate lies about our behaviour, the historic truth of our real failings gives them credibility.

We think of Britain as a model of democracy and the rule of law. In many ways, I believe this image to be accurate. But our failure to stand up to torture and those that use it casts a dark shadow over us all. And this perception is granted greater credibility since during the Cold War, in Northern Ireland, during decolonisation, or in Iraq and Afghanistan, British treatment of prisoners has on numerous occasions fallen far short of what is acceptable.

As the Senate report explicitly states, and as FBI sources corroborate, we could have acquired information faster and more effectively without resorting to torture, using only proven interrogation methods. Shamefully, we have deceived ourselves into believing in the efficacy of torture, and the result has been numerous unnecessary or counterproductive military operations. And as a result we have become our enemies’ most effective recruiting sergeant.

When I discussed this a few years ago with a former head of MI6’s anti-Soviet operations, he was unswerving and unforgiving in his opposition to torture. His biggest criticism is that we just don’t learn. Broadly speaking, in the Second World War the Gestapo used torture and we didn’t. They lost and we won. Then in Kenya, Cyprus and Northern Ireland we let our standards drop and we lost. We failed to heed this lesson when dealing with al-Qaeda.

The country that fails its own moral standards fails the test of history. We are now fatally undermined on the world stage, ill placed to pass judgment over despots on the terrible abuses they inflict, or lecture China on her human rights abuses. Our association with torture causes us to lose our moral strength and serves to galvanise those who oppose us.

Rejecting torture is more than just abstaining from using such techniques ourselves. We have a moral obligation to stand up to those who use torture for their own ends. This is especially true when standing up to our allies. The ‘special relationship’ should mean that we can be frank with each other.

We must send a message that we will not accept the use of torture and any country that wants to have constructive diplomatic relations with us must do likewise. We must refuse to use information gathered under torture, regardless of the security benefits. We must remember the lessons that so much blood and suffering have taught us. Torture can never be tolerated.